test: read the Jest holdout list from one shared module

[cryptodev-2s]

Explanation

PACKAGES_ON_JEST lived in yarn.config.cjs while oxlint.config.ts worked the same fact out for itself by probing the filesystem for packages/*/vitest.config.mjs. Two sources of truth for one question, and they could disagree: a package listed as a Jest holdout that also has a vitest.config.mjs would get Vitest globs from oxlint while constraints demanded Jest scripts.

The list moves to test-runners.cjs and both read it. CommonJS, because yarn.config.cjs is CommonJS and has to require it; oxlint.config.ts reaches it with createRequire rather than relying on module interop. That also keeps the "do not add to this list" note next to the data it governs.

One deliberate loss: oxlint no longer discovers runners from disk, so it depends on the list being accurate. That is the point. Stripping the scope to get a directory name is safe because yarn.config.cjs already constrains every package to be named @metamask/${workspaceBasename}.

test-runners.cjs carries an import/unambiguous suppression, as every other .cjs file in the repo does.

References

• Follows a review question on test: add Vitest alongside Jest #10546, which is where the duplication was spotted
• Stacked on test: add Vitest alongside Jest #10546, and meant to merge before the per package PRs so they edit test-runners.cjs rather than the inline list

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed
  • Not applicable, test only change. Carries the no-changelog label.
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them
  • None.

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Note

Low Risk
Config-only refactor for lint and Yarn constraints; wrong list entries could mis-apply Jest/Vitest Oxlint rules on test files but does not affect runtime product code.

Overview
Centralizes the Jest holdout package list in new test-runners.cjs so Yarn constraints and Oxlint agree on which packages still use Jest vs Vitest.

yarn.config.cjs drops its ~100-line inline PACKAGES_ON_JEST set and requires the shared module instead. oxlint.config.ts stops inferring runners from packages/*/vitest.config.mjs on disk and loads the same list via createRequire, then splits package dirs into Jest vs Vitest test globs from that data. An import/unambiguous suppression is added for the new .cjs file.

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